DIY Magnetic Stereo Contact Microphones

Use PETG or stronger. It also sounds better than PLA, from my testing. For fun, I tested running them over with my car, and leaving them outside during a thunderstorm / all night, and they still worked. So pretty hardy!

Parts

• 27 mm piezo disc(s) (or smaller)

• 20 mm magnet(s)

• any audio cable (for stereo, aux to RCA cables are great)

• silicone or epoxy

• 4x M3 screws (short ones... I don't remember :/)

Steps

• Solder the wires to the piezo disc(s)

  • See my old guide here for more info

• use super glue the magnets into place. This is tricky, since you want the magnet to protrude just a tiny bit. Might take a couple of tries.

  • Pay attention to the polarity if you want them to snap together easily for storage

• super glue the piezo disc to the magnet. Use a bunch to make sure the space between the disc and the magnet is filled.

• Route the wire around the outer shell and out of the hole. Tack it into place with super glue

• Fill the cavity with silicone. Overfill it a bit.

• Place the top, and screw in the M3 Screws in the corners

Notes

This is like the 10th version of a contact mic set. I learned various lessons along the way including:

• Supporting the wire is very important. Hence the wrapping around the whole case strategy

• Epoxy is annoying and hard to get of. Silicone is a bit more forgiving, waterproof, and as far as I can tell does not negatively affect the sound. 

• Buying or making a contact mic pre-amp makes these sound way better. true for any contact mics.